This invention relates to a packaging machine and to a method of filling flexible pouches with product, introducing steam into the filled pouches to remove the air therefrom, and then sealing the pouches.
In the packaging of certain products, and particularly food products, the filled and sealed pouches are delivered to an autoclave and are heated to high temperatures so as to sterilize the product in the pouches. In order for this packaging process to be successful, it is important that the sealed pouch be substantially free of air when the pouch is delivered to the autoclave. If any significant amount of air is present in the pouch, the air will expand when subjected to the high temperatures in the autoclave and will cause the pouch to balloon, such ballooning sometimes destroying the seals of the pouch. Even if the pouch is not subjected to autoclaving, it is often desirable to remove the air from the pouch so that the product will be packaged in an oxygen-free environment and will possess a long stable shelf life.
One known method of producing substantially air-free pouches is disclosed in Wilson U.S. Pat. No. 3,845,606 in which filled pouches are advanced through a retort containing steam and then are sealed while still in the retort. Another method takes place in ambient atmosphere rather than in a retort and involves the use of a packaging machine of the same general type as disclosed in Bartelt U.S. Pat. No. 2,649,674, a machine of this type being known in the industry under the trademark BARTELT. With such a machine, the pouches are advanced first through a filling station where product is introduced into the pouches. The pouches next are advanced to a steaming station where steam is introduced into the pouches to drive the air out of the pouches. Thereafter, the pouches are advanced out of the steaming station and into a sealing station where the open ends of the pouches are sealed. All operations take place while the pouches are in ambient atmosphere and thus it is not necessary to provide a retort for maintaining an environment of steam.